90378 - QUANTUM CHROMODYNAMICS

Course Unit Page

Academic Year 2020/2021

Learning outcomes

At the end of the course the student will be able to: i) describe the main aspects of the phenomenology of strong interactions; ii) master and present the concepts, mechanisms and formalism at the base of the Quantum Chromodynamics; iii) apply the theoretical formalism to cases of interest in high-energy physics and perform computations of relevant observables.

Course contents

1. From Maxwell equations to the QED Lagrangian. Scattering amplitudes and cross sections in QFT. QED Feynman rules and Ward identity. Muon pair production in e+ e- annihilation. QED as an abelian gauge theory.

2. Motivations for QCD. Non-abelian gauge theories SU(N). Feynman rules and ghosts. Colour algebra. QCD as a non-abelian gauge theory with symmetry group SU(3).

3. Renormalisation of QCD, running coupling constant and the beta function, asymptotic freedom, renormalisation group.

4. e+e- annihilation into hadrons at LO and NLO. Cancellation of infrared divergences. Infrared-collinear safety. Jets.

5. Hadrons in the initial state. Deep inelastic scattering, the parton model, structure functions, parton density functions. Infrared divergencies in the initial state. Collinear factorisation, splitting functions, DGLAP evolution equations.

6. Brief introduction to the Standard Model.

7. QCD at colliders. Modern experiments and phenomenological studies.

8. QCD at low energy. Effective Lagrangian and chiral symmetry.

Readings/Bibliography

Books:

• M. E. Peskin and D. V. Schroeder, An Introduction to Quantum Field Theory, (Addison Wesley, 1995)

• R. K. Ellis, W. J. Stirling & B. R. Webber, QCD and Collider Physics, (Cambridge, 1996)

• Chris Quigg, Gauge Theories of the Strong, Weak and Electromagnetic Interactions (Princeton University Press, 2nd edition 2013)

• J. M. Campbell, J. W. Huston and F. Krauss, The black book of Quantum Chromodynamics: A Primer for LHC Era, (Oxford Press, 2017)

• F. Halzen and A.D. Martin, Quarks and Leptons (Wiley, 1984)


Lecture notes on QCD:

• Paolo Nason : Introduction to QCD [PDF] ] [1998]

• Michelangelo Mangano : Introduction to QCD [PDF] [1999]

• Gavin Salam : Elements of QCD for hadron colliders [PDF] [2011]

• Michael Peskin : Simplifying Multi-Jet QCD Computation [PDF] [2011]

• Peter Skands : Introduction to QCD [PDF] [2012]

• Fabio Maltoni : Basics of QCD for the LHC : pp->H+X as a case study [PDF] [2014]




Teaching methods

Blackboard lectures. Slides might be used to present auxiliary material.

Assessment methods

Exercise from the log book, presentation of the final project (to be chosen by the student among a list that will be published at the end of the course) and interview.

Office hours

See the website of Tiziano Peraro